/*
 * Copyright (c) 2016, 2019, Oracle and/or its affiliates.
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are
 * permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this list of
 * conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of
 * conditions and the following disclaimer in the documentation and/or other materials provided
 * with the distribution.
 *
 * 3. Neither the name of the copyright holder nor the names of its contributors may be used to
 * endorse or promote products derived from this software without specific prior written
 * permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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 */
package com.oracle.truffle.llvm.runtime.nodes.asm.support;

import java.math.BigInteger;

import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;

/*
 * This functionality is in the standard class library since Java 9:
 * https://bugs.openjdk.java.net/browse/JDK-5100935
 */
public class LongMultiplication {
    private static long high(BigInteger x) {
        BigInteger hi = x.shiftRight(64);
        return hi.longValue();
    }

    @TruffleBoundary
    public static long multiplyHigh(long u, long v) {
        BigInteger x = BigInteger.valueOf(u);
        BigInteger y = BigInteger.valueOf(v);
        BigInteger z = x.multiply(y);
        return high(z);
    }

    public static long multiplyHighUnsigned(long x, long y) {
        long high = multiplyHigh(x, y);
        return high + (((x < 0) ? y : 0) + ((y < 0) ? x : 0));
    }
}
